Synthesis Of CsPbI₃ Nanocrystals Via Surface Passivation And Their Application In LEDs

All inorganic cesium lead halide perovskite(CsPbX3,X=Cl,Br,I)nanocrystals(NCs)have attracted considerable attention and have been described as the most promising next-generation optoelectronic devices due to their tunable optical properties,high optical quantum yield and simple preparation process.However,their stability in various environments remains to be addressed to enable their exploitation in devices.Here we studied a simple hot injection synthesis process of all inorganic CsPbI3 perovskite nanocrystals based on surface ligand passivation method,and a LED device was prepared based on the obtained CsPbI3 nanocrystals and its performance was evaluated.The thesis mainly obtains the following results:1.The effects of the amount of TOP,reaction time and purification operation on the optical properties and morphology of CsPbI3 nanocrystals were investigated,and the optimal synthesis process was obtained.The prepared nanocrystals were monodisperse with high quality and improved stability.At a certain reaction temperature,the activation energy of the precursor was improved after the introduction of TOP,which was conducive to the construction of good surface structure of nanocrystals and the improvement of their photoluminescence performance.2.Based on the promotion of precursor activity by the TOP ligand,a quick and simple synthesis method of CsPbI3 perovskite passivated by DDAB was proposed.DDA+has a strong attraction to anions,and the iodine-enriched surface structure was constructed.The multi-branched structure of shorter carbon chains in the DDAB molecule can effectively passivate the surface,and is beneficial to the transmission of photo-excitons.These CsPbI3 perovskite nanocrystals were used in the light-emitting diode(LED)showing a maximum external quantum efficiency(EQE)of 1.25%,luminance of 468 cd/m2 and demonstrating improved operational performance.3.The effects of temperature,light and water on the photoluminescence properties of CsPbI3 perovskite nanocrystals capped with different ligands were investigated.Due to the better surface passivation by the new ligand system and lower surface defect density,the cesium lead halide perovskite nanocrystals synthesized by TOP-DDAB had better comprehensive stability.